1. Field of the Invention
This invention relates to a device for marking hidden flaws, such as delaminated areas, in a structure such as a concrete slab, and methods of using the device.
2. Discussion of the Background
Methods of and devices for detecting the presence of hidden flaws within steel reinforced suspended concrete slabs have been suggested in the prior art. The flaw to be detected is a separation, or delamination, of the layers of concrete within the slab. The delamination is caused by corrosion of the reinforcing steel within the slab. Corrosion of the steel within the suspended concrete slab is caused when moisture and chlorides make contact with the reinforcing steel. Once the steel begins to corrode, oxidation occurs and the cross-sectional dimension increases which causes areas within the concrete slab to debond and separate into two or more layers. This condition occurs in areas where there are freeze-thaw cycles as well as in areas where there is a preponderance of chlorides, either air-borne or where de-icing salts are used for roadways and bridge decks. Once the oxidation and the resultant delamination starts, the rate of deterioration accelerates until a condition exists where large concrete fragments break loose and fall, or, in severe cases, a serious compromise in structural soundness of the slab occurs. Early detection, therefore, of the unseen delamination is important to keep repair costs to a minimum.
In the past, detection of delaminations in the bottom exposed surface of a suspended concrete slab, or soffit, has been to repeatedly tap the surface, usually with a hand held hammer producing the sound which has been found to occur when the slab is delaminated. This method of initially detecting the presence of delamination is regarded as a reliable means to find problem areas which are not visually apparent. Most soffits are out of reach, so a ladder or scaffolding is usually required to reach the surface.
At the time the delamination is detected, it is both customary and necessary to then mark the delaminated area, such as with a marker for future repair. For soffits and other hard to reach places, the same ladder, scaffolding or other aid is used for the marking as well.
I have invented a relatively simple and inexpensive rotary percussion tool for detecting delaminations in structures subject to such delaminations, and particularly such structures, such as suspended concrete slabs or soffits, that have previously not been tested for delaminations without great effort. The tool and method of use thereof is the subject of U.S. patent application Ser. No. 09/413,812, filed Oct. 7, 1999, and is hereby incorporated by reference. The tool comprises a rotary percussion tool head adapted at an end thereof to connect to an extension pole, wherein said head comprises at least one circular member, each circular member having on the periphery thereof projections extending in the radial direction and spaced apart in the circumferential direction.
However, a need still exists in the art for a relatively simple and inexpensive device for marking such delaminations